The present invention relates to use of a valve particularly but not solely referring to an improvement in the control over the flow rate of gaseous fuels.
It is well known in the art that a simple rotating ball valve may be used to control the flow of gases. However, such prior art devices commonly suffer a lack of control in adjusting the flow rate to anything other than a high setting. For example, consider FIG. 1, with a graph comparing flow rate against control rotation for a typical prior art valve. There is a very abrupt change between the low setting 11 and the high flow rate setting 12, which occurs over a very small angle as is therefore very hard to accurately achieve flow rates in between these settings. This is particularly important in applications such as a gas cook top where, for example, a chef might require very fine control over the heat applied to the cooking vessel in order to achieve a particular style of cuisine. This may require either remarkably dexterous control over the gas valve or intricate mechanical arrangements in order to improve the level of control, especially at low flow rates.
For example, Korean Patent 9208198 issued to Rinhai Co discloses a solenoid valve in order to electronically achieve improved control over the flow rate over a wide range of flow rates, U.S. Pat. No. 5,009,393 issued to Harper-Wyman Co discloses a linear turn down metering valve with improved controllability. This device however is difficult to manufacture and is quite complicated in construction. It would be desirable to have a simpler construction and to use more efficient materials.
It is also well known in gas valves to have the valve going from the high flow setting to the off setting and vice versa in one movement. This is so that when the burner or heater is started the maximum flow rate of gases is supplied to assist the correct ignition of the flame. It would be dangerous to start the flame with a low flow setting as if the gas was not to ignite a build up of gas could occur with a resulting danger of explosion. Accordingly conventional gas valves only allow rotation to the off position in one direction and have a stopper to prevent any rotation between the low flow setting and the off flow setting. However it would be desirable to allow the gas valve to be switched off from a low flow setting but to also ensure that the gas valve could not be switched on to a low flow seeing from the off setting.
Accordingly it is an object of the present invention to provide an improved gas valve which goes some way to overcoming the above disadvantages, or which will at least, provide the public with a useful choice.
In a first aspect the present invention consists in a valve for controlling a flow of fluid comprising:
a body portion including a fluid inlet and a fluid outlet through which said flow of fluid pass in use, and
control means for restricting said flow of fluid between said fluid inlet and said fluid outlet located within said body portion and adjustably rotatable therein,
wherein one of said body portion or said control means includes a tapering groove on an annular path and the other includes a port intersecting with said annular groove such that the position of said intersection varies according to the angular position of said control means, such tat in use there is a gradual variation in the flow rate of said flow of fluid with respect to variations in the angular position of said control means, over a substantial angle of rotation of said control means, said intersection being within a flow path between said fluid inlet and said fluid outlet.
In a second aspect the present invention consists in a valve for controlling a flow of fluid comprising:
a body portion including a fluid inlet communicating with at least two outer faces of said valve and a fluid outlet through which said flow of gases pass in use, and
control means for restricting said flow of fluid between said fluid inlet and said fluid outlet located within said body portion,
wherein said body portion and said inlet is adapted such that in use when a number of said valves are ganged together their respective said fluid inlets interconnect to form a common fluid inlet.
In a third aspect, the present invention consists in a valve for controlling a flow of fluid comprising a body portion including:
a fluid inlet and a fluid outlet through which said flow of fluid pass in use, and
control means for restricting said flow of fluid between said fluid inlet and said fluid outlet located within said body portion and adjustable rotatable therein,
wherein said control means, at least in a substantial portion, is comprised of a plastics composition.
In a fourth aspect the present invention consists in a valve for controlling a flow of fluid comprising a body portion including:
a fluid inlet and a fluid outlet through which said flow of fluid pass in use, and
control means for providing a variable restriction on said flow of fluid between said fluid inlet and said fluid outlet located within said body portion between a low flow setting and a high flow setting and for preventing said flow of fluid in an offsetting,
wherein said control means is able to switch directly between said high flow setting to said offsetting and vice versa, and further is able to switch directly from said low flow sewing to said off setting but is prevented from watching directly from said off setting to said low rate setting.
To those skilled in the art to which the invention relates, may changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the scope of the invention as defined in the appended claims The disclosures and the descriptions herein are purely illustrative and are not intended to be in any sense limiting.